A. Field of the Invention
This invention relates to stabilized antimicrobial agents, and more particularly, concerns the stabilization of microbial agents against thermal, oxidative, and/or ultraviolet light degradation and their use in the melt spinning of thermoplastic materials in fiber manufacturing.
B. Description of the Prior Art
Antimicrobial agents are incorporated into thermoplastic fiber materials in order to protect the fiber materials against bacterial attack and to reduce the occurrence of mildew and other undesirable growth on the fiber in its final form, such as carpeting.
During the manufacture of synthetic fiber, the antimicrobial agents of the fiber are exposed to very harsh conditions. For instance, the agents of the fiber are melted with thermoplastic polymers and held at elevated temperatures prior to spinning. During spinning, the agents are subjected to high pressures and are further heated because of friction during their extrusion. Furthermore, the extruded filaments containing the antimicrobial agents are exposed to atmospheric gases during their processing. Because of these harsh conditions, the antimicrobial agents can undergo thermal degradation.
Antimicrobial agents are also subject to oxidative degradation when the agents are exposed to contaminates which cause oxidative degradation. This problem is particularly acute when the contaminate and antimicrobial agents are exposed to moisture and/or heat or are present with the antimicrobial agents at high temperature, i.e., melt-spinning.
Furthermore, antimicrobial agents are subject to deterioration when they are utilized in an outdoor environment or otherwise subjected to ultraviolet light radiation.
As a result of either thermal, oxidative, or ultraviolet light degradation on the antimicrobial agents, the agents lose some or all of their potency. Therefore, large amounts of antimicrobial agents must be included in synthetic articles such as films or fibers to ensure that the article has sufficient resistance to microbial attack.
Thus, there is a need for antimicrobial agents which have increased thermal, oxidative, or ultraviolet stability, and combinations thereof. By the present invention, stabilized antimicrobial agents are provided, as well as articles such as fibers, which contain the stabilized antimicrobial agents.